Mr Obama called for a "new chapter" for the graft-riddled regime and Gordon Brown said he would no longer put British troops "in harms way" to defend a corrupt administration.

In the conspiratorial world of Kabul politics, many will see the leaking of Gen Eikenberry's concerns and his mention of corruption as another attempt to squeeze Mr Karzai.

Mr Karzai's government is totally reliant on Western backing as he has lobbied for the maximum increase in troops requested by Gen McChrystal.

London and Washington both face waning public support for the war and each is grasping for levers to exert influence on a regime they are loosing patience with. The threat not to send those troops is one such lever to get my Karzai to clean up his act.

However many diplomats question the effectiveness of such leverage.

They say Mr Karzai believes he has the US and the UK over a barrel after the summer's painful election campaign showing there was no credible alternative leader. While promising change, Mr Karzai's palace has become irritated at the barrage of threat, blaming much corruption of poorly run Western aid contracts.